As a model structure for the linkage of antigenic polysaccharides in bacterial cell wall, we propose to study the phosphate diester bridge between the antigenic polysaccharide composed of 2-acetamido-2-deoxy-D-mannuronic acid and D-glucose residues to C-6 of the muramic acid residues of the peptidoglycan in Micrococcus lysodeikticus cell wall. This study will include a search for the lipid intermediates in the biosynthesis of the antigenic polysaccharide elucidation and purification of the enzymic system responsible for the transfer of the completed polysaccharide chain to the peptidoglycan, as well as the chemical synthesis of the isoprenoid sugar phosphates intermediates.